Insulation is an essential component of every residential and commercial building project. To meet today’s requirements for energy efficiency and comfort, homeowners and architects need to consider insulation in the entire building envelope. From the roof to the foundation, insulation is key in reducing energy usage and loss.

Heat naturally flows from warmer to colder areas unless a barrier prevents the flow. In cold weather, heat can leak out of a building into the colder outside environment. Thermal insulation resists this heat transfer.

Measuring insulation performance

There are several ways to evaluate how insulation performs, of which the R-value is the most commonly known. R-value measures the thermal resistance of a material per a given thickness. Insulation with higher R-values are better at resisting heat loss or gain. Historically, foam insulation and fiberglass were the primary insulation options available. Recent advances in rigid insulation board technologies are now allowing for code compliance at the same R-values as bulkier materials, but in a thinner thickness. This allows for thinner walls which results in more natural light and usable interior space.

Additional factors within a building’s structure also affect possible energy loss and how insulation performs. Thermal bridges, like wooden studs, are pathways in a building structure through which heat can escape. These can be significantly reduced through the use of continuous insulation.

There are various types of insulation available including spray foam, rigid board, fiberglass batts and mineral wool.

The importance of moisture

Another factor affecting building performance is moisture control. Moisture and condensation can reduce the performance of certain types of insulation and lead to mold growth when trapped within walls or ceilings. Moisture control within a building is challenging because it is affected by many things including climate types, ventilation and wall assembly design.

The proper installation of insulation also has a significant impact on moisture control. Placement of a vapor control layer on the warm side of the insulation helps to prevent water vapor from moving from the warm side to the cold side of the assembly, where it is more likely to condense. It depends on the climate type and wall assembly as to whether the vapor control layer needs to be placed on the interior or exterior side of the insulation. Buildings in colder climates generally have vapor control layers on the interior side of the insulation.

Getting a good assessment

With so many factors affecting performance, a good assessment to complete is a hygrothermal, or condensation risk, analysis of the building design. This assesses the risk of condensation forming within the wall assembly once the insulation is installed by predicting the dew point temperature. This can help guide the selection and installation of the insulation.

There are various types of insulation available including spray foam, rigid board, fiberglass batts and mineral wool. These vary in price, performance per inch of thickness and application usage. For a wall or under-roof (attic) assembly, the highest performing insulation types are phenolic, PIR (polyisocyanurate), spray foam and mineral wool.

Many power companies share home performance data with homeowners and show them how their home is performing compared to similar and energy-efficient homes. They also suggest investing in things like energy efficient appliances to save on energy usage. Commercial buildings waste up to 30 percent of the annual energy use according to Energy Star.

It starts with the building envelope. Upgrading appliances, HVAC systems and lighting are only a few ways of increasing energy efficiency. As a passive measure with no associated on-going operational cost, upgrading the building envelope can often play a critical role when it comes to driving down energy costs and improving building performance.